I wrestled with this dilemna myself some time ago. I finally settled on the Large for the following reasons:
1. $699 on sale for the new model (longer handle).
2. Eggcessories seem to be more plentiful for the Large.
3. When I built my midi UDS (18.5"), I almost never used my bigger drum.
4. I figured that it would make more sense to buy a second egg at some point (maybe a Medium) for more space or keeping a different temp going e.g. cook steaks on one then move to another to sear or vice versa.
5. I heard that the XL can be a fuel hog.
I've been very happy with my LGBE so far.
EZ wood handled 3 wheeler | OTS | OTS mod to OTG | Ladybug SS Performer | UglyDrumTandoor | UDS v1 | midi UDS with red nipples | SJG smoker mod | Simpsons SJS | Simpsons OTG | WGA charcoal | SJP | Stacked brick WFO | Lodge Logic Sportsman's Grill cast iron hibachi/sigri | LBGE | sbge | mini bge