The Paterson tanks/reels seem to be pretty popular:
Jobo is another very popular and flexible system. I use Jobo 1500 series tanks and reels for developing my film and love them.
Buy Jobo 1520 UniTank with 1501 Reel featuring Includes One 1501 Multi-Format Reel, For Up to Two Rolls of 35mm or 120, Supports Inversion or Rotation Processes, Plastic Design, Light-Sealed, Daylight Tank, Expandable with Optional 1530 Accessory. Review Jobo null
www.bhphotovideo.com
Some people prefer stainless reels/tanks. If you go that route, the Hewes reels are considered by many to be the best:
Buy Hewes 35mm Stainless Steel Developing Reel featuring Durable, Easy-to-Load, Handy Sprocket Tabs, Superbly Engineered. Review Hewes null
www.bhphotovideo.com
You can find used steel tanks from brands like Nikor on eBay for reasonable prices.
I personally find Jobo reels easier to load than steel reels, but that's just me.
To black out my darkroom space, I installed 6 mil plastic material over the windows. No light penetrates that material.
Buy Delta 1 Black Out Heavy 6 Mil Plastic Opaque Material 4 ft.x 16 ft. Roll Review Delta 1 null
www.bhphotovideo.com
There are many blackout drapes/blinds sold on Amazon that claim 100% opacity, but I've never personally tried them.