Is it too personal? Sorry, i had no idea. Then i guess if i was to buy one for first time, what would you decide is best?
It's fine, don't worry!
And hmm.. My personal favorites are the Forget-me-Not valley entries, A Wonderful Life and DS. I don't know if that would be a good place to start though. AWL is pretty different in that a lot of focus is on your family and mainly your kid, I loved it and the whole entire environment but it's also very slow compared to others and there aren't really any goals like some games have. Harvest Moon DS is also full of bugs, and if you're going to get into the older handhelds I'd recommend (More) Friends of Mineral Town anyways.
Friends of Mineral Town is good though, I'd recommend it if one of the older games sound fun. There are also different versions with the same characters (I think Harvest Moon 64 and Back to Nature) but I was never able to play those. Apparently those are really good too though.
Tree of Tranquility for the Wii was also fun, and it also has a second version called Animal Parade with some new stuff. I own both but I've only finished Tree of Tranquility. From my boyfriend who I don't think really likes these games, he said Animal Parade was REALLY good.
After ToT I kind of stopped enjoying the newer releases, but the newest Story of Seasons was actually pretty fun too. I liked the farming mechanics this time around, it felt a whole lot more rewarding and fun to grow crops. Some of the requirements are pretty hard though, and there is so much of everything it can get a little more complicated than the older ones.
Since this thread is about Natsume's versions of Harvest Moon, I guess I'll go ahead and also recommend those. I've only played Lost Valley and it wasn't my cup of tea, but I could see how someone could still have a lot of fun playing it (if I didn't have any ill thoughts towards it, I actually probably would've really enjoyed it.)
Sorry I just ended up listing different games without picking one for you. There is a lot of variety, and you can even look around for others too if you want! These are just my personal favorites.
Sorry if I'm getting really off topic!