RCU Forums - Which engine??

RCU Forums (https://www.rcuniverse.com/forum/)

- Car Nitro & Gas Engines (https://www.rcuniverse.com/forum/car-nitro-gas-engines-269/)

- - Which engine?? (https://www.rcuniverse.com/forum/car-nitro-gas-engines-269/7777964-engine.html)

My Go Tech 7 port has lost almost its compression after 3 gallons and the lack of low end is noticeble.
I'm considering buying one of these engines. I am open for other suggestions. Pros&Cons?

Picco P7R EVO 2
Picco P7R EVO 3
OS MAX V-SPEC T
Ofna Jamin
Novarossi RX21P5XS 5 port
RB Concept S7 L2G
Ninja JX Buggy Engine .21 5 Port
O'Donnell Super Sport .21cu in (3.4cc) Off-Road Engine

Sorry about the long list, but I'm really uncertain about which engine to buy.
I want an reliable engine that lasts more than 3 gallons, with good fuel consumption. Any suggestions?
Thanks

RE: Which engine??

The RBs are Great motors The S7 would be great I have 2 of them. Maybe consider an S5 as well both are great motors and should last for many many gallons. I am running S5 right now in my buggy and S7 in my Truggy.