I like the EF2C a little more than the Vali2, but mostly because I like the tube type the EF2C uses better for options for tube rolling. The DAC on the EF2C is terrible though. Luckily I don't use the DAC and never planned on using the DAC. The EF2C pairs very well with the HE400I. The stock tubes the EF2C comes with are pretty mediocre though. With the stock tubes the HE400i is a little piercing. I put voshkods in mine and it really sings.
Fullness and warmness will mostly depend on the tube with both amps. You can have everything from syrupy bloated bass and rolled off highs with some mallards to bright with the stock Chinese tubes.
Overall, if you like the tube family of the vali2 I think it's a slightly better built amp, but with both these amps, the tube is king, so your sound will depend more on what tube you end up with than the actual amp itself. If you aren't sure which tubes you'd like, go for the vali2