im at a situation where i think my alliance is not active enough or not good enough
even though they are rank 1 and are doing quite well

if i leave them will it be good spirit?

or how can u suggest i leave?

It depends on the situation. If you jump ship in the middle of a war, then you're just leaving them for dead which would not be good spirit.

If you're not at war and you explain to them that you expected more out of the era and you feel the alliance you're in can't offer that, they can either up their game or accept they aren't trying hard enough and allow you to find a team where you feel the players will be more suited to your playing style.

However you can play as clean as you like, if the alliance doesn't want you to join another alliance they could just kick and conquer you before you have a chance to move on. So it's always a tricky one on deciding whether your alliance will agree with your decision or it's best to explain after you've relocated and ready to join another alliance. Doing it this way is in bad spirit, however if you don't trust the alliance you're in enough to tell them how you feel then you can't be blamed

Just don't leave when the alliance requires you the most. Make sure they can fill your position comfortably and give them a reason as to why you left and all should be okay.