I've met a number of the actors through the years. Fortunately no bad experiences with any of them. Here's my impressions of each:
William Shatner - I'd heard stories about him being rude and not even speaking to fans, so when I said "hi" to him and got a "hi" back I felt pretty good, lol. He was perfectly polite for the short time I had with him.
Leonard Nimoy - About the same as Shatner. Very polite, but not much time with him as there was a huge line.
George Takei - Very chatty and friendly, seemed to be having a great time.
Walter Koenig - More reserved, but very nice
Patrick Stewart - Polite and dignified, just got a cursory greeting from him as we were being rushed through the line by the organizers
Jonathan Frakes - Really friendly and likes joking with fans
Brent Spiner - He was with Frakes when I met him, very nice
Michael Dorn - Very nice but more reserved
Avery Brooks - One of the friendliest I met. At our photo op he pulled me in for a big hug, very outgoing and loved engaging with fans
Nana Visitor - Lovely person, very friendly
René Auberjonois - Nice guy
Armin Shimerman - Very friendly and was having a good time
Robert Picardo - He was more reserved but seemed to be having fun
Jeri Ryan - Very beautiful in person, sweet and friendly
Scott Bakula - Very down to earth and a nice guy
Connor Trinneer - Extremely nice and engaging guy, he even showed up at the bar to chat with fans. My dad was with me and was thrilled to get to talk to him as he hadn't bought any autograph or photo-op tickets.
McKenzie Westmore - Met her at a Passions event, very lovely
Chase Masterson - Very nice
Dean Stockwell - Reserved but very polite
Christopher Lloyd - Friendly and nice