2C engines are nice to run, its simple to use. The TT46Pro is totally reliable, so are engines like SC/MVVS/OS etc. Of course 4C engines are nice, you have to choose between a 70 sized (OS70FS, Saito 72/82) or a 50 sized one (Saito 56 Magnum 61 OS 52). If you just want to enjoy the 4* and not bother about how fast the plane is gonna go then any 50 sized 4C will be fine but then later on when you want to move on that engine choice will kinda limit your options. For me its the SA82, best choice on the basis that its more versatile. Still engines like the Magnum 61 is cheap, very reliable and fuel consumption is very very good.

Anyways, how high are you at?