to each their own honestly, as far as regulators go.
I went with UP Aqua because of the price, haven't had any problems, concerns, etc. with it so far. At the same time, I've never used anything besides that to compare it with. I got it for like $85 total I think on amazon at the time.
You could basically go with any bubble counter, I got a cheap, I believe UP Aqua, one that does a good job, just your basic bubble counter with an integrated check valve.
A diffuser is something you don't want to skimp on, not sure what the better ones out there are, but you want something that will atomize/break down the bubbles really well so that it'll break down into your water faster rather than larger bubbles.
Drop checkers are great to have too. I again went the cheap route and I think got a basic aquatek one. I'd have preferred to get an all glass one just for the looks, but this does it's job well enough for now. Make sure you invest in some 4dkh solution to go with it I think you can get a 2-3oz bottle on eBay for like $8 including shipping and it'll last for a very long time. Drop checkers aren't accurate without that solution, unless you want to make your own, which becomes a PITA fast.
Basically, it all depends on your budget, if you don't want to spend a lot you can get it all for a fair price and it'll work just fine (IMO) but spending a bit more wouldn't hurt. If I were to do it again, I'd still go with everything I have but I'd go with more a more esthetically pleasing bubble counter and drop checker.
I think that's all I have to add.