These are a few of my favorite things:

ROAD iD

I've been using some sort of ROAD iD product for over a decade. I currently use the Sidekick model on my Garmin watchband. Do yourself and your loved ones a favor and purchase (and wear) a ROAD iD. A great, practical, common sense safety investment.

Hygiene

Squirrel's Nut Butter is my go-to anti-chafe product.

Anti-Chafe Salve before runs
Saddle Butter Cycling Salve before bike rides
Happie Toes to treat my feet after long runs or wet runs (also works well on dry skin in winter)
Born to Rub helps if I'm experiencing pain or discomfort with a joint or muscle.

Orange Mud Transition and Seat Wrap - This towel is very versatile. I keep one in the trunk of my car, and I always take one with me if I drive to an event, run, or ride. The zip-up hood feature which goes over the headrest on a car seat makes this super convenient, since you don't have to worry about the towel slipping down on the seat.

Running

Running Shoe "Hall of Fame":

Altra Escalante Racer - From the moment I put this shoe on, it felt perfect. It continues to impress!
HOKA Carbon X
Saucony Kinvara 9
Brooks Catamount

Apparel:

Patagonia Strider Pro Running Shorts - Love the pockets for carrying nutrition on longer runs.
Rabbit FKT 3" Split Short - Comfortable waistband, side nutrition pockets, rear zip pocket that comfortably holds my phone.
New Balance Heat Grid 1/2 Zip - The material is warm and comfortable. Plus there is a double zipper, from the sternum to the neck, so you have a variety of thermoregulation options.

Running Accessories:

Rudy Project Rydon sunglasses with Photochromic Clear to Black lenses - The light transmission range from 9% (darkest) to 74% (lightest) makes these incredibly versatile. I use a Rudy Project prescription adapter.
UltrAspire Lumen 800 Multisport waist light - I originally purchased this for nighttime use during ultramarathons but also routinely use it for general nighttime running. Comfortable, convenient, and really lights up the ground and surroundings.
Altra Trail Gaiter - These gaiters conveniently velcro to the back of Altra trail shoes and hook at the bottom of the tongue. They are lightweight, breathable, unobtrusive, and do a great job keeping debris out of shoes.
Amphipod Trans4m™ Thermal Plus™ Run Glove - I was skeptical when we started stocking these in the store; but, after trying them out, I soon realized they are incredibly practical. Being able to fold back the finger cover allows for effective thermo-regulation. These also layer well on top of another glove to provide wind protection and additional warmth. An incredibly versatile cold weather running accessory.

Cycling

Bikes:

2017 Cannondale CAAD12 Road Bike w/ Shimano Ultegra R8000 Di2 with 52/36 x 11-30 gearing - I bought this bike when I got into cycling in 2017 and have upgraded nearly everything. The frame, fork, crankset, and chainrings are original, but pretty much everything else has been customized. (Mostly lives on the indoor trainer these days.)
2017 Trek Boone 7 Cyclocross Bike w/ SRAM Force CX1 46 x 11-36 gearing, Mavic Allroad Elite UST wheelset, WTB Riddler 700x37c tubeless tires, Fi'zi:k Vento Argo R3 saddle, and Garmin Rally XC200 power meter pedals - Apparently no one wanted to buy rim brake cyclocross bikes in 2017 once disc brakes were becoming ubiquitous. Trek ended up discounting these heavily. I've also customized this bike, and I especially like the simplicity of the 1x drivetrain. (Go-to bike for most outdoor training rides.)
2019 Trek X-Caliber 9 Mountain Bike w/ Fi'zi:k Tempo Argo R3 saddle and Bontrager Line Elite dropper seatpost.
2021 Specialized Tarmac SL7 w/ Shimano Ultegra R8100 Di2 with 52/36 x 11-30 gearing and Garmin Vector 3 power meter pedals..

Indoor Training Set-Up:

Tacx Neo 2 Smart Trainer
Saris MP1 Nfinity Trainer Platform - This makes multi-hour indoor rides so much more comfortable. It also makes getting out of the saddle more realistic.
Zwift - Subscribing to Zwift was a game-changer which has made indoor cycling so much more enjoyable.

Cycling Shoes:

Fi'zi:k Transiro Infinito R1 Knit shoes for my road bike
Fi'zi:k Infinito X1 shoes with SPD cleats for my cyclocross bike and mountain bike

Helmet:

Bontrager XXX WaveCel Road Bike Helmet - I strongly recommend getting a helmet with additional anti-rotational protection such as WaveCel, MIPS, or SPIN.

Cycling Accessories:

Garmin Varia Rearview Radar - In addition to serving as a taillight, it alerts you that vehicles are approaching from behind. Seeing the alert on the Garmin Edge bike computer provides advance notice of approaching vehicles. This is an additional safety feature that I greatly appreciate when riding on the roads.

Electronics

Fitness Tracking:

Garmin Enduro 2 smartwatch (previously used Forerunner 945, Forerunner 945 LTE, and Tactix Delta and recommend any of them)
Garmin Edge 1040 Solar cycling computer (previously used Edge 530 and highly recommend it)

AfterShokz Aeropex (now called Shokz OpenRun) bone-conduction wireless headphones - I really appreciate that these don't go in or cover my ears, and that I am able to hear my surroundings while listening to music or podcasts. I routinely wear these while on training runs or while riding the indoor bike trainer. I do not use headphones when I run on the trails or participate in races. I also don't wear headphones when cycling outdoors.

Theragun Elite - Using this percussion massager after a hard workout or a long day makes my muscles feel a lot better. The travel case is compact and convenient. I initially questioned the usefulness of the Bluetooth and smartphone app, but I have found myself using the guided sessions in the app fairly regularly.