2 very different amps. For you I would say go with the Hartke, because it is closer in sound to the Fender Rumble you use today. But that's just IMO.
Either one of the choices will be a decent step up for you.
I currently have a PF500, and have used an LH500 as a backup amp in the past (no longer own it).
PF amps are all SS with Class D power sections
LH's are Class A, with big iron trannys and tube (12AX7) pre's
PF amps offer 350w and 500w
LH's are 500w and 1000w
PF amps have the classic Ampeg Baxandal tone stack
LH's have the classic Fender style tone stack (passive mids)
PF amps are true lightweights
LH amps are a bit heavier (but not back breakers)
Both companies make good gear and have solid reputations. I'm pretty sure that both amps come with a 2 year, non transferable warranty (I know this for sure about the Ampeg, but you should check this detail on the Hartke's).
If you like the Fender Rumble you have been using so far, you will find the move to the Hartke LH amps simpler because they sound very similar and have a common tone stack/EQ design.
The Ampeg PF series do deliver the classic Ampeg tone which is great for rock (and all styles of music really), but you will have to twist some knobs a bit to get used to the different (Baxandal) tone stack/EQ. Not very hard, but you will have to adjust.
have fun getting your new amp.