Well whilst hq4x looks a lot better in your comparison than it does in mine. I would still pick either bilenear or 2XPM HQ over it. Things tend to get distorted and lose their original shape and texture with hq4x. Whilst I do want to play on a larger screen I want it to stay as true to the original as possible and hq4x simply distorts too much. If I do find things too blurry then I would use X2PM HQ or hq2x. I understand it's matter of taste, I just simply wanted to point out why I prefer the smaller filters.
If you use the additional TV scanlines or Bilenear Plus filters then the blur is a lot less noticeable, although the colours take a hit due to them and their darkening of the screen.
For Warioland4 I must admit it looks better...but then again that screen shown is not exactly very complex, there are lots of simple shapes which are easy to smooth, like squares and triangles there...if however you try it on a much more detailed screen...say something like Golden Sun or a fight in a Final Fantasy game things would not look anywhere near as good. Costumes would get messed up, swords would lose their shape and various other distortions would occur.