Hello, hello, hello, hellos.
Best is subjective.
I have an ICS brand, Sig Saur 556 which outguns some TM M4/M16's at my local site.
If you have experience with "real steel" you may find Airsoft a little disappointing due to lack of noise, recoil, weight etc. That said, this can be countered by modification, upgrades and weapon choice.
My advice here would be to find a local site, have a go and chat to the regulars about thier guns. We are essentially a bunch of anoraks and revel in people fawning over our guns. In most cases we'll let you have a go too. This will be beneficial to you as you can try a variety of different weapon types and find out what arena they excel in.
Tactically you may find milsim more "appealing" than the paintball type games of capture the flag, king of the castle etc. Again these game types do carry their own merit and are fun, fast paced experiences.
The advice of getting your 3 games in and registering yourself as a skirmisher with UKARA (this is your defence for owning a Replica Imitation Firearm in accordance with the VCRA) is sound. Plus most sites (especially MilSim) don't allow two tone weapons as it detracts from the "realism" of the scenario.
In the meantime I would suggest that you find yourself some good eyepro (I favour the mesh goggle type over ballistic glasses as nothing is likely to get in - although never say never), some variant of face protection (some sites won't let you play without a mask - I personally rock out with only eyepro, either a baseball cap/boonie and a scrimscarf) and a good, sturdy pair of boots (I have Hi-Tec Magnums which I love but there are many other good makes out there).
That means minimum outlay and just hire cost which works out great if you decide you don't like the sport.
Have a good read about on here and utilize the search function. There's a wealth of info here that money just can't by.
Most of all, have fun.
Welcome to the weird and wonderful world of Airsoft bro.