I like using this site to kind of monitor the crowds for a few days to guestimate how crowded it'll be. If that makes sense... www.isitpacked.com/
And if they're scared of coasters... I think SFMM is the WRONG place to be. LOL! But, to answer your question... X2.
(totally kidding!)
It's summer so it will be busy. Saturdays are busiest followed by Sunday and then Friday then weekdays (barring events/deal days)
Best to show up at least 45 mins prior to park opening to get far ahead enough in line that you have your choice of first ride with no line. For making the most of your time I recommend starting with YOLOCoaster if you arent purchasing a platinum FP and a $15 YOLO ride. If you do that you can come back to X2 at about 4:30pm when the line will be minimal. Tatsu can be ridden anytime using a flash pass (if you're going on a weekend, get a gold flash pass).
If the person is literally afraid of all coasters she may be right..he might be in for a boring day. Ironically back when I was still afraid of "extreme" coasters I was dragged onto X as my first ride of the day. I wasn't happy about it as I was going up the lift hill, but I was pumped up when I got off and ready to ride again. It certainly is a good trial by fire. If you think it would be wiser to warm them up on something first, Colossus and Gold Rusher are the best non-kiddie starters. I would say Revolution, but pain can turn people off of coasters and that thing is nothing if not painful. (Same reason why I wouldnt recommend X2 even though I started on it, its very painful right now)
Whatever you do, don't put them on Green Lantern first, they may never go near a coaster again! lol
Oh! Also, there is a phone app on iOS and Android called "RideHopper" that can sometimes give pretty accurate info on wait times. It's user input based, so there's always the potential that someone misjudges time or trolls bad info, but the more submissions they get it averages out and SFMM gets more input than any other so it's usually pretty good. Theyve taken steps to make it more accurate by only allowing those in the park (checking GPS) to input times and it also has a built in timer so you can start your time when you get in line and then post the time it took when you get to the station. Recently the Android version also added alerts so you can set it to "Alert me when the ride has a wait of < or > # of minutes"
Just don't take the times literally, use it more as a guide to see whats busy and what isnt (or whats closed). I believe its 1.99 on android but free on iOS.
I was hoping to get them over their fear. Green Lantern first it is [emoji14] Thanks for the advice and suggestions.