mhiebl, welcome to the forum, benvingut!
Since you are in a large city like Barcelona, I would definitely consider second hand. 200 € can get you a fine pair of brand new binoculars... but it can get you some seriously good second hand. I'm sure there is a good and large enough pool of 2nd hand binoculars within your range, that you can go and touch, try for yourself (something you could not do living in the countryside), so I'd take advantage of your situation. You can search in milanuncios, wallapop and the like.
I have not tried exactly the formats you mention, but in other parameters I have owned both the Pentax SP WP (it was a 10x50) and I own the Nikon Action EX (7x35). I got both second hand for less than 100 € each and I think they are very nice pieces of equipment, with a performance way above their price (and I don't mean the 80-90 € I paid for them, even at 150-200 €).
Pentax: The build quality of the Pentax SP WP was veeery nice, it reminded me of the Zeiss Conquest HD, not much behind honestly (I'm talking about the feel of the rubber armour and general feel of the binoculars in your hands). But the field of view was quite narrow, only 5º for a 10x, that was the reason I sold it. Otherwise, they were quite bright and the view was sweet.
Nikon: The Nikon Action EX was a big surprise for me; I didn't expect much, and I really like it. It is a 7x with 9,3º FOV, which feels so nice. Obviously a big part of that field is not really usable, but the nice feeling of 7x (great depth of field, really inmersive) plus the 3D effect provided for the porro really make them something to take into account. But, there is always a but: they are quite clunky and heavy. And not only that; I find them pretty large for my hands; I'm 1,78 with accordingly average hands and depending on the position of my hands, sometimes I find it a bit hard to reach the focus wheel (obviously, forget about "single-hand" them; at least in my case). I tried the Aculon 7x35, which is newer and supposed to have some improvements in the optics... but I found it to be way inferior, both in optical performance and in fit and finish.
So, SP and EX, both fine, but both pretty hefty and clunky; which might be of consideration depending on your needs: do you plan to do some trekking/walking with them, or will you be stationary or drive by car? I don't know the kind of birdwatching you plan to do, but honestly in Barcelona it's usually quite sunny
... so maybe you should consider a 8x32 as someone mentioned already. You could find really nice things for 200-250 € in that format, especially if you go 2nd hand.
Hope that helps
