As far as amplification type goes, single ended triode (SET) is probably the most popular amp type to go with Omegas, but push pull (PP) amps also work very well but with a slightly different flavour. In the solid state realm, pure class A, class D, and class A/B chip work really well.
In pecking order as far as brands of amps go on the Omega AC forum I would say Decware and Linear Tube Audio for tubes. For solid state, First Watt, Temple Audio, and a well built TPA3116 based class D DIY amp.
I was an Omega dealer for 8 years, and found any of the Decware SE84 Zen amp iterations to be my personal reference. If you want a good education on tube amps, spend some time on the excellent Decware website.