In general, amplifiers are happier into a high impedance load, as long as they aren't driven into clipping. So assuming all else is equal (which of course it never is), I'd suggest 8 ohms if there is no danger of clipping and 4 ohms if there is.
Now all else is never equal, and apparently you've already found speakers you really like, and unless their impedance curve is really funky they'll work fine with both your amps. Having "speakers you really like" outweighs any theoretical/speculative "amps are happier with higher impedance unless blah blah". So go for it!
Now all else is never equal, and apparently you've already found speakers you really like, and unless their impedance curve is really funky they'll work fine with both your amps. Having "speakers you really like" outweighs any theoretical/speculative "amps are happier with higher impedance unless blah blah". So go for it!