There are sooo many choices and i'm not even kidding.
1. McClicky: Very good and my personal choice. The max rating is 4A (but will not melt until after 7A) at 12V DC for 10 000 actuations. The resistance (as measured by Dan at Oveready) is 92% of a ZeroRez tailcap. You can get Soft, med or hard press boots easily.
2. Kroll Tailcap: Not made anymore but you can still get them at TheSandwichShoppe (i can link you if you wish). Some people prefer the shape (conical), as it is easier to actuate.
3. Netkidz: Not made anymore but you might be able to snatch it up on the B/S/T. An alternative to the McClicky.
4. FETtie: Made by VanIsleDSM in the custom B/S/T. This is the most advanced out of all of them, as it is essentially like a relay (think of a solenoid in your car) that can easily handle 400W of power or 20+ Amps without breaking into a sweat. The resistance is the lowest out of all of them so you WILL get more light in direct drive setups and more runtime in regulated setups. Available in both forward or reverse configurations.
5. Stock Z58: Is a clicky, but not recommended for higher powered drop ins like Quads/trips/XMLs as the max current rating is 2.5A. Higher resistance than a McClicky and no room for changing boots etc.
There are 2-3 more but their name escapes me. Hope that helps! Personally, i've owned pretty much all of these 5 and McClicky is still my favourite
The only downside really is less output in my FM1794 setup and less runtime in my 5.6A quad. But i can handle a 15% loss on both accounts.