Raven or General Dynamics for a 1.8 antenna?

IMHO: Want better reception - get bigger dish! I've found it useless to look which antenna works better. Too many factors are involved here- LNB and feedhorn used, cabling, connectors, precise positioning of the feed, weather conditions, time of the day.... etc. But size of antenna is still same, which is 1.8m. I think all 1.8m antennas, if perfectly aligned and proper feed is used, will perform more or less same. And, in fact, it is not proper to say that antenna "A" is better than antenna "B"! They both just piece of metal or glass, they can be differently colored, they can have different weight , different strength ribs, different mounting system, different price.... etc. But when we speak about performance, than we better speak about performance of the satellite system (the mirror itself, plus LNB, plus feed, connectors, cables). So, IMHO again, want better performance of your satellite system- get bigger reflector, for example 2.4m. Satellite system based on 2.4m reflector will surely outperform any other on 1.8m reflector size based satellite system.
Reflectors, made for Ka-band reception have better quality of the reflective surface, but they probably more expensive than reflectors made for Ku-band.

I have a Channel Master 2.4m offset antenna, at least 4-5dB more than the 1.2m Channel Master antenna. If you have a 1.8m of this quality you won't find anything better without going bigger as Rima suggests above, other than spending another few hundred $$ on top of the line LNB, which you have likely done that already.
The 2.4 also works well on C-band where most of the interesting signals are on Anik G/F1.
FTA wise of course.

What antenna size does Shaw recommend for your area? Thinking an 84e would be awsome unless you are way out of the satellite broadcast area.

Are you using a scaler that is matched to the dish? If not that might get you a little bit more signal. A higher stability LNB.... but you say you already have a great LNB. I believe I once saw a post somewhere of someone using a precision oscillator and also cooling the LNB for less noise, but other than for an experiment, it would not be practical for home use.

Just curious, what feed horn & LNB(s) combo are you using?