The "best" is the one being maintained by the same outfit teaching you. Why??...because when it is pissing down with rain and blowing a gale outside you, the Pilot Operating Handbook (POH) and a warm mug of coffee will at least get to sit for several comfortable, undisturbed and free hours in the cockpit, in the hangar, running through those important checklists and all your procedures until you are memory perfect. Better than that...you will also get to quiz the mechanics. A smart pilot always sticks close to those who really know where to look for that hydraulic leak on preflight inspection, what fire detector sensor usually gives the false alarm and why, and which instructor is known in the repair hangar to be the firm's biggest liability. Best advice is to learn in something small, like an R22; plentiful, thus cheapest, and lots of maintenance going on. Later you will move onto turbine engines and much more complex systems, for that is all larger helicopters are. Again, then the lads and lasses in the maintenance shed will be your greatest teachers. Above all, start small and build up. It worked for me. And while we are on the subject, always remember:...Know safety, no pain. No safety, know pain.