It depends on your design but if I wanted use a design for high frequencies, I used through hole just for power/heating parts and used SMD for the rest because SMD design can reduce inductance and resistance of component parts .
Advantages of SMD:
1-Smaller components.
2- Much higher component density (components per unit area) and many more connections per component.
3-Lower initial cost and time of setting up for production.
Fewer holes need to be drilled.
4-Simpler and faster automated assembly.
5- Small errors in component placement are corrected automatically as the surface tension of molten solder pulls components into alignment with solder pads.
6-Components can be placed on both sides of the circuit board.
7-Lower resistance and inductance at the connection; consequently, fewer unwanted RF signal effects and better and more predictable high-frequency performance.
8-Better mechanical performance under shake and vibration conditions.
9-Many SMT parts cost less than equivalent through-hole parts.
10-Better EMC compatibility (lower radiated emissions) due to the smaller radiation loop area (because of the smaller package) and the smaller lead inductance.
Disadvantages of SMD:
1- Manual prototype assembly or component-level repair is more difficult
2-SMDs cannot be used directly with breadboards
3-SMDs' solder connections may be damaged by potting compounds going through thermal cycling.
4- SMT is unsuitable for large, high-power, or high-voltage parts, for example in power circuitry.
5-SMT is unsuitable as the sole attachment method for components that are subject to frequent mechanical stress
The answer to your question depends a lot on how the SMT connector is applied.
The SMT connector can be rather robust if you have large copper areas that surround the mounting pads. If you just place small pads that are just barely bigger than the SMT leads then it will be much easier to rip the connector off the board.
Another very big contributing factor is how the SMT connector and its board are packaged. If the connector body overhangs the edge of the board and then fits through a nice snug rectangular opening in the housing then most of the mechanical stress of cable pulling laterally will be absorbed into the housing instead of through the connector mounting leads.
If you have any concerns at all then stick with the through hole part. That is what I do. And on top of that the through hole part takes up less area on the top side of the board and provides good high current connection to the bottom side of the board as well.
Best Answer
What Oli says, BUT BC337-40 (NPN) and BC327-40 (PNP) through hole TO92 transistors will meet 95% of your small transistor needs, and they have the direct equivalents of BC817 / BC807. The SMD versions are available in Asia as Leshan Radio parts (NPN & PNP through hole and SMD) with similar part numbers - LRC817, LRC807. These are genuine Motorola mask parts made by a joint venture company between Motorola and LR. They have a range of older lower tech Motorola parts plus their own parts as well. Some of their own parts are very useful.
LR transistors page 1/3
For larger wattages, higher voltage or current, low noise high FT etc search Digikey [As trav1s suggests] for "transistor" follow the yellow brick road (menu selections) to the relevant selector guide and enter required parameters. Digikey transistors end of yellow brick road is here . Then sort by price and choose the cheapest in stock at the required volume - or use this as a guide to buy elsewhere. Consider using only ROHS compliant parts.
If a part is too special to succumb to these methods, ask us here with a specific design question.
Taiwanese CETSEMI also make some extremely nice transistors and small MOSFETs. The CETSemi CES2310 will do most things that an amateur would expect a SOT23 N Channel MOSFET to do.