KENTUCKY!!! Horse Country
We have 3 or 4 mini clubs -- The Kentucky Horse park has 2 shows a year there -- AMHA and AMHR -- the State Fair has a show -- Close to shows in TN, OH, IL, IN, MO and not too far a drive from nationals in TX and OK. Great DRIVING activity here too -- with VSE classes in ADS (and CAA) shows -- Great places locally (in the LEX area) to take your horse for recreational drives -- even places to stay overnight and drive during the day - LOTS of fun -- Almost all of the local county fairs have mini classes in them (halter and driving) -- and the local Mini club(s) have competitions and year end awards for who wins the most of the country fair classes (and the fairs a lots of fun too!).
On the other hand -- its not cheap!
Lexington area Local Real Estate Website (LBAR)
I live in the Georgetown area -- north and further east of me it gets pretty hilly (as in vertical hills, but not mountains) -- Shelbyville/Taylorsville is a nice area too -- Nicholasville and Harrodsburg are great
Again, you will need to see places in person to see if they are flat or rolling or steep -
We get some winter, but really nice Spring/Fall - and a bit on the warm side in summer. Tornado's are our big threat (like the other states you mention). Hurricanes are normally all gone to rain by the time they make it up to us. We get ice storms some times -- but they are rare.
Its beautiful here -- people are very helpful and very friendly -- back roads are NARROW - but scenic and you get used to driving on them -- horse trailers and horse vans are EVERYWHERE!
Close to excellent miniature horse sales (Little Kings, Bluegrass Mini Club) - and there are so many great mini breeders in this area.
I have lived in TN, GA, NY, AR, TX, KS and here - this is my favorite of all.
Good luck where-ever you choose to live.
JJay
PS - next door to us is 10 acres for sale with a pond, mostly fenced perimeter - no buildings on it yet -- for $60,000 (I believe that is the price they are asking - its for sale by owner) and it has a gentle roll to it. Nice people in the neighborhood and 30 minutes from downtown Lexington in rush hour traffic. If we had the money, we would buy it.