All else being equal.............................

Since i'm not a fan of Krell's latest offerings, I would lean toward the Hegel. Bare in mind that i've read commentary on here & on other sites reporting there is a difference in sound between the H200 & H300, and some owners on here prefer the sound of the H200. Unless you need the H300's included dac or digital inputs, I would suggest reading up on threads here discussing the two amps. Here is one example.

With the above said, if you're open minded about other potential options it would be helpful to know you budget, accompanying equipment (amps, speakers & cables) and approximate room dimensions so members can offer more appropriate advice.

Since you're the TUBEmeister, contemplating SS, check out the tube/SS hybrid Ypsilon Phaethon

Fla, that might be over his budget. He could look at a Dealer ex demo Aesthetix Atlas Signature tube hybrid amp & Janus Signature pre. That is a nice combo & would be good value. Otherwise a 2nd hand Vitus RI-100 is an awesome ss integrated and has excellent power.

If solid state is your preference, I second the darTZeel LHC-208 'danalog' Streaming dac with integrated amplifier. This line of electronics is the finest sounding solid state one can purchase and while they seem expensive, they are cheap when you consider the superior sound.

I recently heard the Hegel 300 and liked it, though maybe not enough to trade in my Modwright to get the Hegel. Also tried the Vanguard at home recently. Also very nice but much more sharply etched than either the Hegel or the Modwright. That extra detail is both a blessing and a curse depending on the source material.
FWIW the Hegel H200 is discontinued so that may be hard to find.