Well, i've tried Mechwarrior Online and it sucks. Badly.
Best mech games are still Mechwarrior 2 and Mechwarrior 3 and Starsiege (Earthsiege 3).
MW2 in Pentium Edition with VGA software graphics that still give me the chills and I don't even want it to run in 3D accelerated form. Because that will ruin the gritty feel of it.
Mechwarior 3 because of the amazing mouse control and how weapons feel (especially those machine guns and chainguns)
And Starsiege because of interesting weapons that have a range delay and you have to rely on on-board prediction system. And i totally loved to upgrade shields, reactors and weapons because they visualized everything with amazing graphics. Like armor composite was displayed in molecular structure, reators with blue glow, sensors, on-board computers etc. It was just freakin awesome.