Time to be a curmudgeon...
Each has it's place... for sure... but...
I feel strongly that bipolar transistors are easier for newcomers to electronics to deal with. Unless you are trying to drive a relay yanked out of an Automobile whose coil might draw hundreds of milliamps, your average 2N2222 transistor will easily drive a small relay. No issue with heat... geez the 2N2222 IS BARELY working hard to drive a simple relay like that.
Read the WIKI on the 2N7000 mosfet and then read the 2N2222. Literally interchangeable and 2N2222 might even be superior.
How often have we seen people misuse/misapply the IRF510... because they thought a MOSFET is a MOSFET... or because they thought it was just BETTER to use one and it ends up being a complete waste of (or lack of) engineering if used to drive a 5V relay in a 5 Volt circuit.
Now driving a 12V Relay... where you really are driving the relay with 12 volts... and the relay draws more than the average hundred or so milliamps... maybe an IRF510... (you need a extra level converter transistor too) but the relay is supposed to SAVE you from doing the heavy lifting... which is why many draw less than 100 ma and most are between 100-300ma. A 2N2222A can cope with up to 800ma and you usually only need to add a 1K resistor at the base.
If it's a 2N7000 NCHANNEL MOSFET or 2N2222 NPN transistor you are going to spend about $0.50 for either one, on average.
If you are using anything in a T0-220 package to drive a relay... you wasted your money.
Logic Level Bipolar transistor... Um... no. that's not a problem when dealing with standard transistors.