Eheim, Fluval or Tetratec are generally all good filters.
As for size whatever floats your boat. Providing you have sufficient filter for the fish you keep then its fine, rememmber theres no such thing as over filter. Personally i always over filter. I run a 70L with a Fluval 205 and 180L with a Fluval 305
I have a 95ltr/20gallon tank and have been running a tetratec ex700 for months, it's very easy to set up and service etc, I liked it so much I just received delivery of a second one which I'm running tonight
£60.00 from warehouse aquatics, very easy to use
A simple 125 litre tank can be well filtered by a Rena XP2 or even a Rena XP1. I run a 55 gallon tank with an XP2 as its only eater source and it does fine. I also run a couple of 29 gallon tanks on XP1 filters without many problems. Your tank is intermediate between my tanks and I would say that any filter designed for a 30 gallon or larger tank would probably work well in this situation.