What type of oven generally is best?

I personally like convection ovens for bread and pastry (or any other type of baking for that matter) with the exception of things like pizza, naan, etc.  I prefer a brick or open hearth stone oven for those purposes.   Convection ovens require a bit of time to learn but, in the end, I think you'd like that design.  "Not-so-expensive"?    You get what you pay for.

If you buy a convection oven make sure you can turn the convection feature off, or at least on very low fan speed.  I've found that custard based items like custard pie or pumpkin pie tend to burn before they set unless you turn the temperature way down.  But when you do, you end up having to bake the item twice as long as you would have if you had baked it in a conventional oven.

...I have a conventional oven that doesnt work as well in giving me steady temps in the 300-500 range...

In my experience, a home oven that doesn't provide steady temps up to at least 450F is extremely unusual. It's not so clear to me that replacing the oven with something else is warranted as the best solution. (Often home ovens, especially those without really good insulation ["self-cleaning" is a good proxy for lots of insulation], start to have problems around 500F. If you have one of these ovens, one solution is just to bake bread at a slightly lower temperature.)

(Home ovens are frequently "off", so for example 350F on the knob is really 325F. But when this happens, the "off" temperature [325F in this example] is "steady", not a surprise; it's not something that only happens on Wednesdays:-)

(The way ovens work is by cycling back and forth between a little below the desired temperature and a little above the desired temperature. So for example if 400F is desired and is dialed in to the controls, the actual oven temperature may keep shifting between 375F and 425F to average the desired 400F. This is just the way ovens work; it's perfectly normal; it's not something to fret about or try to "fix".)

This sounds to me like either a) a worn out door seal or b) a control that's gone nuts and needs to be replaced [or maybe c) a misleading way of measuring oven temp]. "Convection" ovens are currently popular  ...but I doubt "convection" is the solution to your problem.

A decent oven thermometer is vital. It should stay in the oven all the time. Find a way to position it so it's out of the way of your baking, not too close to the heating elements, and with a minimum of the metal housing of the oven thermometer touching metal inside your oven. I've found hanging it works well, either from a piece of purpose-bent coat hanger wire or from an empty rack on the top notch.

(Any oven will drop temp if you open the door a lot or leave it open for more than a few seconds. No matter what kind of oven you have, it will be important to open the door as few times and as quickly as safely possible. The inevitable loss of temp when opening the oven is a big reason why home bakers often say to preheat the oven at a little higher temperature than the baking temperature, then turn if down a few minutes after the bread has gone in.)

Have you tried having the thermostat replaced?  That's number one......and the cheapest.

For baking bread, I would definitely prefer an electric oven over a gas oven, as they retain moisture/steam inside the oven much better than a gas oven. Look for one that has a completely sealed bottom, rather than one that has a seam around the bottom. For convection, the more fans, the better.

Thank you very much it's very useful. I have been try to get information for my new oven also. This is just the answer what I'm searching for.