Once breastfeeding was going, the young baby bit was nice until they got mobile and was a blessed relief after the pain of pregnancy. DS1 in particular indulged me with a luxurious 2 hours sleep at a time which was lovely after waking hourly from SPD & carpel tunnel.
The terrible twos from 10m to 5y were awful. Undiagnosed ASD and food allergies explain a lot. At a combination of 1-2/ 3-4 I'd often have to leave DS1 threatening to dig through to Australia to chase the houdini DS2. At least he was very un-abducatable. There was a sweet spot at 6. Then SATs at 7 and the 4 hour meltdowns triggered referral. Things settled anyway and the diagnosis and realising DS1 is neurodiverse has helped a lot.
I've made it to 10 & 8 so far and the junior school years are generally good other than Covid lockdowns screwing up DS2's world and creating social and confidence issues by tearing up his friendship groups and trapping him with only DS1 for company for far too long.
DS1 being neurodiverse is a big influence. We lurch from adult conversations to very young emotional outbursts and as he spends much of the time masking and presenting "normally" he looks naughty despite putting a lot of effort into managing his moods.
The teenage years will present different challenges to them both. DS2 for the independence/ social life, DS1 for getting through school life. At least unlike the toddler years, I understand what makes him tick and he has got a functional vocabulary.
Unbroken sleep makes a massive difference. They're low sleep anyway and child-free evenings are not a thing. It makes such a difference not having to supervise everything and being able to go to the post box in 5 minutes rather than an hour's epic of getting dressed and trudging to the postbox of umpteen meltdowns as in the toddler years. DS1 will also appreciate being able to spend time alone and this has begun when I'm local.
I think I can sumarise it by the fact that I quench any broody urges by repeating the word "toddlers" until the feeling passes. It used to be such a relief to drop them at nursery and have a relaxing day teaching teenagers in a school in special meaures! 
I do totally love them by the way! 