I fly exclusively business class on Air Canada and Lufthansa. And cattle class on Yemenia. Luckily the Yemenia flight is only about 2 hours long. I total about a 100,000 miles a year.
Air Canada’s business class is a combination of first and business called Executive/First. They don’t have an exclusive first class service. It is better than Lufthansa’s business class service. Both are far better than in the back with the goats and chickens.
I’ve flown first class on upgrades with Lufthansa between Frankfurt and Dubai. While it offers larger chairs than in business class you still couldn’t lay flat out as the middle of the chair had a 2 inch drop in it right at your hips, so in order to get comfortable you had to adjust the seat into a partial sitting position that didn’t give you any better position than in business class. Air Canada’s business/first is better than Lufthansa’s first in my opinion. This varies by airplane, of course. Maybe you’d end up with the new seats that allow you to recline all the way. But, you wouldn’t know until you got on the plane if this was so.
Another few annoying things I’ve found out about flying first class (at least on Lufthansa) the few times I’ve been in it.
The meal service took 3 fricking hours! I wanted a quick meal after travelling all night from Calgary on Air Canada. Half the flight was taken up with this service. Almost everything was done at the seat with the damn cart blocking all egress until they were finished farting around before going on to trap the next row of hapless passengers.
When they were serving cheese each piece of cheese was cut as requested using mini utensils that seemed useless for the task. Watching the waitress try and cut this milk white gooey cheese for about 5 minutes with a dull butter knife left me feeling very nauseous indeed<blerk!>. It didn’t help that the guy sitting next to me had to try every combination on the appetizer cart multiple times over (speaking of farting. Can you imagine what caviar, sour kraut, and eggs does to a person who overindulges? Yeah, it is best to be avoided). A guy I was travelling with a few rows back who also got bumped up to first said the women sitting next to him ate all three choices for the main meal. It seems people want to get their money worth and eat the extra hundereds or thousands of dollars they paid.
Unless they offered you a free upgrade stay away from First class. It isn’t worth putting up with all the hoity toityness. Business class is worth it unless you are young and nimble enough not to be paralyzed by sitting in a chinese torture box for 12 hours, or so.
Another rule:
Get an aisle seat when sitting in cattle. That way you can stick your feet in the aisle for more room. You won’t sleep so it doesn’t matter if people climb over you to go to the washroom, but that extra room is heaven. Also, never ever, ever, sit in the middle unless you are travelling with people you know on either side of you. There is nothing like getting stuck between Gargantua and his cousin, Bigfoot.
In business and first, always take a window seat. You can sleep here. I prefer climbing over others when I need to get out than having others climbing over me when I am asleep. This is especially true if you are unlucky enough to sit next to the ‘drunk’ who takes advantage of all the free booze. You don’t want the drunk climbing over you to get to the washroom. No sir, no sirree. You certainly don’t want that. At least if you have to climb over him, you can get some revenge for the wine he spills on you by ‘accidently’ stumbling while doing the ‘hop’ over his footrest and landing a knee to his groin. 
Then there are all the snifflers, coughers, and pukers. Oh, my!
Hmmm… Yeah, if I was you I’d just stay home!