As R4 suggested, a comprehensive water analysis and report is needed. Also useful is the usual number of house occupants.
Since you are on our own private well, there is no one to test and verify that your water is safe. That responsibility falls on you as the well's owner so your water should be tested on a periodic but regular ongoing basis.
Included in the test will be an indication of contaminates and minerals present in the water sample. Knowing the quantity of hardness (calcium and magnesium), iron and manganese are particularly needed when choosing the size of softener. Depending on the quantity of iron, or if sulfur is also present, other types of water treatment methods may also be necessary.
I have an old softener not worth fixing.
Describe the age of the 'old' softener and post some photos especially of the controls, front and back. A good quality control valve (ie: Fleck, Clack, Autotrol) will typically provide 10-20+ years of reliable service. Even very old ones, may often be rebuilt utilizing new seals, spacers and other low cost parts, to restore them to 'like new' operation.
The one says I should get the timed one because I am on a well, and metered are more for city water. Is this true?
No. A timer is an old method for initiating a regeneration cycle. With a timer, regeneration will occur whether all softening capacity has been utilized or none at all.
Metered controls have become common as they are considered to be more salt and water efficient since they will normally only initiate regeneration after a set amount of softening capacity has been actually utilized. For this reason, some states are now beginning to require metered controls while timed controls are being outlawed for new installations.
With regard to a new softener, many online dealers do not include nor even mention gravel under-bedding. That is a layer of gravel at the bottom of the tank which helps to protect the bottom screen and also distributes water flow throughout the resin bed above.
While a gravel under bed is highly recommended, since most online sellers include shipping in their prices, not including gravel saves them a few $$ in shipping. It seems there are a few online guys that by leaving out the gravel, also downsize the resin tank so by later adding a gravel under bed, there is not enough space remaining for the full amount of resin.
Recommend to:
1) have your water tested
2) post the test results
3) obtain advice and recommendations pertinent to your specific water conditions
4) ask for opinions and recommendations on the specific equipment you are considering