you arent comparing apples to apples it seems. key height (your problem it seems) is completely different than the mechanical vs membrane debate. keys come in full height, half height and then laptop style/chicklet style. your first mechanical was likely a full height key keyboard while your membrane is likely a half height key keyboard. as for which you prefer thats down to your own way of typing and usage habits. mechanics come in both flavors.
as far as the argument is mechanical worth it? maybe. some people like mechanical because they are more precise and do not feel "spongey" like rubber dome keyboards do. some people like membrane keyboards because they are quieter and/or they like the feel of them. some like the mechanical switches which make noise and have tactile feedback for typing. some like the ones without such features for gaming. there are other people who can use nothing but laptop or chiclet style keyboards. honestly... whatever suits your needs is what you should use.
i've used a myriad of different keyboards and that can teach you alot about what you like and do not like. for instance i dont mind higher end membrane keyboards like the ones from logitech since they have very easy to press keys (soft touch i think they call it) but i abhor cheap keyboards with stiff keys (like the one i'm on now). i've used old mechanicals like the model m which is very precise however after using lower height keyboards for awhile its hard to get back into using. i've tried out the cherry mx keyboards and while they arent bad, i think they have a little room to be improved. i dont like how if you spill liquid on them it drains right through the keyswitchs (the model m has a drip pan and isolated switches). i myself find anything comfortable to type on except cheap membrane and laptop/chiclet style boards.
if you went mechanical i'd suggest trying a mechanical with half height keys maybe something like this
https://mechanicalkeyboards.com/shop/index.php?l=product_detail&p=655