Best - hard to pick out one as most were good, or had lots of good bits. But 2005 was the year that Christmas Day was my EDD, I refused to travel "down home" (250 miles) and we stayed at our home. But as I was SO heavily PG, we were able to go to my GPs house for dinner (we always feel that any time we DO stay up, we ought to cook for ourselves just as our core family of 2 and now 3). We always visit my GPs house, even now that they are gone and it's my DAunt's house - she hosts Christmas for her siblings, and there is a big gathering of various relatives and friends throughout the day dropping in for drinks/nibbles. But that year, we went to church in the morning, walked the pier (well, I got 2/3 of the way waddling), visited my other DGM in my other DAunt's house, and then we went to my DGPs house in late afternoon. Where DD had dropped enough to allow me to enjoy 2 helpings of turkey, 2 of pudding, and 2 small glasses of wine. There were 14 there that day (DGPs, 5 of their 6 DCs and the 3 relevant DSpouses, and 3 DGC's (me, a 4 year old and a 5 month old - our respective parents were the eldest and youngest) as well as DH). It was a lovely relaxed welcoming evening, with lots of laughter. I knew before I left that their DGGC was on the way (things started as we left dinner table to open presents but I had to stick it out for another 2 hours) but it was a lovely surprise to them all waking up the next day - I was trying to keep quiet sitting between the other new(ish) mum and the priest!! The mat hosp was lovely and quiet that evening so I was able to stay in the shower for hours, and DD arrived at 6am. By the time that the "family" dinner back in that house in the early new year (when my DF and his family came up to our city - for dinner at his parents house), it was sooo lovely to be home, and to get photos of DGM holding DCousin (5 months) and DGF holding DD (just days) - that is a really special photo showing the bridging of the generations and there's a whole family one showing 4 generations together.
Worst - last year, I found it quite hard. It was the first without any of my DGPs - they died in 2010, 2012 and 2013. All had great lives, and I was very involved with them throughout my own. There was a lot going on and I was running too much. But I didn't have a chance for much needed quiet time and processing time. We have had a few years of rows in my family - but I have learned enough by now to see them coming and get out of the way.